Shock absorber and method of assembly

ABSTRACT

A shock absorber comprising an elongated cylindrical pressure cylinder having a piston reciprocally disposed therewithin and connected to a piston rod extending outwardly from one end thereof, the piston rod carrying a dirt shield which extends coaxially of the pressure cylinder and in partial surrounding relationship therewith. The pressure cylinder is adapted to be filled with preselected quantities of a hydraulic damping fluid and a pressurized gas for damping reciprocal movement of the piston therewithin. The piston is provided with a novel valve arrangement which controls the compression and rebound characteristics of the shock absorber, and one end of the pressure cylinder is provided with a novel rod guide assembly which is designed so as to provide for convenient charging of the cylinder with the aforesaid pressurized gas. The interior of the pressure cylinder is provided with a generally helically shaped baffle arrangement which is compressible axially within the cylinder in response to reciprocal movement of the piston therein and functions to prevent undesirable foaming or aeration of the hydraulic fluid during operation of the shock absorber.

United States Patent [191 Fader et al.

[ Nov. 13, 1973 SHOCK ABSORBER AND METHOD OF ASSEMBLY [75] Inventors:John H. Fader; Johan H. Keijzer,

both of l-lasselt; Marcel J. R. Graulus; Roland H. C. Beets, both of St.Truiden, all of Belgium [73] Assignee: Monroe Belgium N. V., St.Truiden,

Belgium [22] Filed: Mar. 30, 1972 [21] Appl. No.: 239,814

Related U.S. Application Data [62] Division of Ser. No. 45,867, June 12,1970,

abandoned.

[52] US. Cl. 188/322, 141/326, 220/46 P, 220/55 AN [51] Int. Cl.....'.F161 9/36, Fl6f 9/43 [58] Field of Search 188/269, 322; 220/46 P, 55 AN;141/325, 326,327

[56] References Cited UNITED STATES'PATENTS v 2,882,592 4/1959 DeCarbon188/269 X 3,197,191 7/1965 Axthammer 267/64 R 3,287,008 11/1966Fernandez 188/269 X Primary ExaminerGeorge E. A. Halvosa Attorney-4i.Keith Miller 57 ABSTRACT A shock absorber comprising an elongatedcylindrical pressure cylinder having a piston reciprocally disposedtherewithin and connected to a piston rod extending outwardly from oneend thereof, the piston rod carrying a dirt shield which extendscoaxially of the pressure cylinder and in partial surroundingrelationship therewith. The pressure cylinder is adapted to be filledwith preselected quantities of a hydraulic damping fluid and apressurized gas for damping reciprocal movement of the pistontherewithin. The piston is pro vided with a novel valve arrangementwhich controls the compression and rebound characteristics of the shockabsorber, and one end of the pressure cylinder is provided with a novelrod guide assembly which is designed so as to provide for convenientcharging of the cylinder with the aforesaid pressurized gas. The

interior of the pressure cylinder is provided with a generally helicallyshaped baffle arrangement which is compressible axially within thecylinder in response to reciprocal movement of the piston therein andfunctions to prevent undesirable foaming or aeration of the hydraulicfluid during operation of the shock absorber.

AZ )1 5 Claims, 11 Drawing Figures SUMMARY OF THE INVENTION The presentinvention relates generally to shock absorbers of the type used onautomotive vehicles and the like for damping relative movement betweenthe sprung and unsprung portions thereof. The shock absorber of thepresent invention is designed to have the interior thereof provided witha preselected quantity of hydraulic damping fluid and with a preselectedquantity of a pressurized gas which cooperate with one another todamping reciprocal movement of a valved piston located within thepressure cylinder. The piston is provided with a new andimproved valvingarrangement which provides for interchangeability of the valve elementsof the compression and rebound control valves thereof, which valves arelocated on the piston and are adapted to cooperate with a novel bafflearrangement which is disposed within one end of the pressure cylinderfor preventing foaming or aeration of the hydraulic fluid which isundesirable since it prevents positive damping. The piston is connectedto one end of a piston rod which extends axially outwardly from one endof the cylinder and is supported for longitudinal reciprocal movement bymeans of a rod guide assembly located at one end of the cylinder. Thepiston rod carries an elongated cylindrical dirt shield member which isarranged coaxially of the pressure cylinder and is adapted to be securedto the piston rod in a manner so as to minimize the overall size of theshock absorber and provide for economy of production and pleasantappearance of the shock absorber. The rod guide assembly is providedwith a novel sealing arrangement which provides for fluid tightlow-friction peripheral engagement with the outer periphery of thepiston rod and is adapted to be operatively mounted within one end ofthe pressure cylinder in a manner so as to minimize to the extreme, thetime and effort required in charging the interior of the cylinder withthe aforesaid pressurized gas.

It is accordingly a general object of the present invention to provide anew and improved shock absorber for use on automotive vehicles and thelike.

It is a more particular object of the present invention to provide a newand improved vehicular shock absorber of the above described type whichis provided with preselected quantities of hydraulic damping fluid andpressurized gas, and which is also provided with a novel bafflearrangement to prevent undesirable foaming or aeration of the fluid.

It is another object of the present invention to provide a new andimproved shock absorber of the above character which features a valvedpiston having interchangeable compression and rebound valve elements.

It is a further object of the present invention to provide a shockabsorber of the above character which is provided with a novel dirtshield mounting means.

It is still another object of the present'invention to provide a new andimproved shock' absorber of the above described type having a rod guideassembly featuring a novel fluid seal arrangement.

It is yet a further object of the present invention to provide a new andimproved shock absorber of the above character wherein the rod guideassembly is designed to permit effortless charging of the interior ofthe pressure cylinder with pressurized gas or the like.

It is another object of the present invention to provide a new andimproved shock absorber of the above described type which is of arelatively simple design, is economical to manufacture a'nd will have along and durable operational life. i

Other objects and advantages of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinalcross-sectional view, partially broken away, of a shock absorberembodying the principles of the present invention;

FIG. 2 is a view similar to FIG. 1 and illustrates the shock absorbershown therein in a partially compressed condition;

FIG. 3 is an enlarged fragmentary cross-sectional view of the shockabsorber piston embodying certain principles of the present invention;

FIG. 4 is a transverse cross-sectional view taken substantially alongthe line 4-4 of FIG. 2;

FIG. 5 is an enlarged fragmentary cross-sectional view takensubstantially along the line 5-5 of FIG. 2;

FIG. 6 is an enlarged fragmentary cross-sectional view of the piston rodguide assembly incorporated in the shock absorbers of the presentinvention;

FIG. 7 is an exploded assembly view of the rod guide assembly shown inFIG. 6;

FIG. 8 is an exploded assembly view of the dirt shield mounting meansincorporated in the shock absorber of the present invention; and

FIGS. 9, l0 and 1! illustrate various positions of the rod guideassembly upon assembly thereof within the shock absorber of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detailto the drawings, a vehicular shock absorber 10, in accordance with anexemplary embodiment of the present invention, is shown as comprising anelongated cylindrical body member or pressure cylinder 12 which definesan internal chamber 14. The upper end of the chamber 14 is closed by agenerally cup-shaped end cap 16 which has a generally radially disposedupper section 18 and an annular downwardly projecting flange section 20that is adapted to be telescopically received within the upper end ofthe cylinder 12 and be fixedly secured therein, as by welding or thelike designated at 22. The end cap 16 has fixedly secured thereto, as bywelding or the like, a gen erally ring-shaped attachment member 24 whichis adapted to be secured in a conventional manner to the sprung portionof the associated automotive vehicle, as is well known in the art.

Disposed interiorly of the chamber 14 is a reciprocal piston assembly 26which is attached to one end of an elongated piston rod 28 that isarranged coaxially of the cylinder 12 and is adapted to reciprocatetherewithin along with the piston assembly 26. The lower end of thepressure cylinder 12 is provided with a rod guide assembly, generallydesignated 30, which is adapted to support the piston rod 28 forlongitudinal reciprocal movement. The outer end of the rod 28 isprovided with an end cap assembly, generally designated 32, whichcarries a generally cylindrically shaped enclosure member or dirt shield34 that is arranged coaxially of the cylinder 12 and partially surroundsthe lower end thereof, as best seen in FIG. 2. The lower end of thepiston rod 28 is formed with a reduced diameter, externally threadedsection 36 which is adapted to be threadably received within aninternally threaded bore 38 of an annular collar member 40 which issecured as by welding or the like to an annular attachment member 42.The member 42 is adapted to be secured in a conventional manner to theunsprung portion of the associated automotive vehicle in a manner wellknown in the art and thereby functions along with the attachment member24 in operatively supporting the shock absorber of the present inventioninterjacent the sprung and unsprung portions of the vehicle, whereby theassembly 10 will function to effectively damp relative movementtherebetween.

Referring now in detail to the construction of the piston assembly 26,as best seen in FIGS. 3 through 5, the assembly 26 comprises an annularbody member 44 which is formed with a first pair of diametricallyopposed, axially extending bores 46 and 48, and with a second pair ofdiametrically aligned, opposed bores 50 and 52 which are arranged atgenerally right angles to the bores 46, 48, as illustrated in FIG. 4.The bores 46, 48 are formed with a pair of enlarged diametercounterbores 54, 56, respectively, at the lower ends thereof, while thebores 50, 52 are formed with a pair of enlarged diameter counterbores58, 60, respectively, at the upper ends thereof. The upper side of thebody member 44 is formed with a pair of spaced parallel upwardlyprojecting embossed portions 62, 64, and the lowerside of the bodymember 44 is formed with a pair of spaced parallel downwardly projectingembossed portions 66, 68 which are arranged at generally right angles tothe embossed portions 62, 64. The portions 62, 64 and 66, 68 are adaptedto operatively support therebetween a first plurality of valve plateelements 70 on the upper side of the body member 44 and a secondplurality of identical elements 72 on the lower side of the body member44. The pluralities of elements 70, 72 are generally flat andrectangular in shape and are disposed in overlying relationship with oneanother, with the plurality of elements 70 being nestingly receivedbetween the embossed portions 62, 64 and arranged in overlyingrelationship with respect to the bores 50, 52 and the plurality ofelements 72 being nestingly received between the embossed portions 66,68 and being arranged in underlying relationship with respect to thebores 46, 48. It will be ssen that the elements 70, 72 disposed directlyadjacent the upper and lower sides of the body member 44, respectively,extend almost diametrically the entire width of the body member 44, withthe successive overlying or underlying elements 70, 72 associatedtherewith being progressively shorter in length to provide a leaf springarrangement. The plurality of elements 70 are formed with a series ofcentrally aligned openings 74, while the plurality of elements 72 areformed with a similar series of centrally aligned openings 76. Theopenings 74, 76 are all aligned with a central bore 77 formed in thebody member 44 and all of said openings 74, 76 and 77 are adapted tohave a reduced diameter mounting section 78 of the piston rod 28 projectupwardly therethrough, as best seen in FIG. 3. The section 78 of thepiston rod 28 defines a generally radially disposed shoulder 79 and isformed with a reduced diameter externally threaded portion 80 at theupper end thereof, the portion 80 being adapted for threadable receptionof a suitable retaining nut 82 or the like, as illustrated. Interposedbetween the upper side of the valve elements and the nut 82 is a pair ofretaining or bearing members 84 and 86 which define central bores 88 and90, respectively, through which the upper end of the piston rod 28extends. Similarly, interposed between the lower side of the valveelements 72 and radial shoulder 79 is a retaining plate 92 defining acentral bore 94, and a bearing plate 96 defining a central bore 98. Itwill be seen that upon tightening of the nut 82 upon the threadedportion of the piston rod 28, the pluralities of valve elements 70, 72will be forced into compressive engagement with the upper and lowersides of the body member 44, whereby the central portions of theelements 70, 72 will be fixedly secured to the body member 44. Theelements 70, 72 are preferably fabricated of a resilient spring-likematerial, such as spring steel or the like, whereby the outer marginalend portions thereof may be pivoted or biased upwardly or downwardlyaway from the adjacent upper and lower surfaces of the body member 44,whereby to provide for-selective opening and closing of the bores 46, 48and 50, 52, as will be described. The portion of the piston rod 28directly below the bearing plate 96 may, if desired, be provided with aresilient compressible bumper member 100 which is provided with acentral bore 102 adaptedfor sleeved reception upon the piston rod 28 asillustrated. The bumper member 100, upon outward movement of the pistonrod 28 with respect to the pressure cylinder 12 will service as acushioning means upon engagement thereof with the rod guide assembly 30,as will be apparent.

In operation of the shock absorber 10 of the present invention, thebores 46, 48 and plurality of valve elements 72 function in a reboundcontrol valving capacity by selectively moving toward and away from thelower side of the body membr44 and thereby opening and closing a pair offlow paths from the interior of the chamber 14 to the bores 46, 48.Similarly, the bores 50, 52 and plurality of valve elements 70 functionin a compression control valving capacity by moving toward and away fromengagement with the upper side of the body member 44 so as toselectively open and close a pair of flow paths between the interior ofthe chamber 14 and the bores 50, 52, as will be apparant to thoseskilled in the art. A particular feature of the above describedarrangement resides in the fact that the pluralities of valve elements70, 72 are completely interchangeable with one another, whereby tominimize the attendant manufacturing and inventory expenses to theextreme. Additionally, the particular elongated, generally rectangularshape of the pluralities of elements 70, 72 provides for a substantialsavings in material as compared with generally disc-shaped and similarstyled valve elements known in the prior art.

As will hereinafter be described in detail, the interior of the chamber14 is adapted to be filled with a preselected quantity of hydraulicfliud and is also adapted to be charged with a pressurized gas, such ascompressed air, nitrogen or the like. One problem that has beenparticularly objectionable in connection with similar type shockabsorbers heretofore known and used which utilize as a damping medium acombination of hydraulic fluid and pressurized gas, has been theaeration or foaming of the hydraulic fluid which occurs upon reciprocalmovement of the associated piston within the pressure cylinder. Suchfoaming or aeration of the hydraulic fluid is particularly objectionabledue to the fact that the hydraulic fluid'tends to become compressibleand thus adversely affects the damping efficiency of the shock absorber.The aeration problem has been found to be aggravated by the highvelocity flow of fluid through the valving of the associated piston andthus shock absorber assemblies provided with valve pistons has beennotorious for their areation problems.

In accordance with the present invention, the aforementioned aeration ofthe hydraulic damping fluid within the chamber 14 is effectivelyobviated through the provision of a novel-baffle member, generallydesignated by the numeral 104, which is disposed within the chamber 14interjacent the upper side of the piston assembly 26 in the end cap 16.As best seen in FIGS. 1 and 2, the baffle member 104 is of a generallyhelical configuration and has a maximum outer diameter which is designedto be received within the pressure cylinder 12 with slight interferencefit, whereby baffle member 104 is axially movable within the chamber 14in response to axial movement of the piston assembly 26. The bafflemember 104 is preferably fabricated of a resilient material such asspring steel or the like and the radial dimension of each convolutionthereof is designed to project radially inwardly from the wall of thepressure cylinder 12 to a position overlying or in axial alignment withupper ends of the bores 46, 48 and 50, 52 whereby fluid which flowsthrough the bores 50, 52 will impinge against the lower side of thebaffle member 104. By virtue of the helical configuration of the bafflemember 104 and the spring-like character of the material from which itis fabricated, the member 104 is adapted to be compressed axially as thepiston assembly 26 moves upwardly within the chamber 14. Thus, thebaffle member 104 may be compressed, for example, from the positionshown in FIG. 2 to the position shown in FIG. 1. In accordance with thepresent invention, at leat a portion of the baffle member 104 isdisposed below the fluid level within the chamber 14, i.e., is submergedwithin the hydraluic damping fluid, which arrangement has been found tooptimize the action of the baffle member 104 in preventing aeration orfoaming of such fluid. It will be noted, however, that even where thebaffle member 104 has no portion thereof submerged within the fluid,said member 104 will be found to operate highly efficiently inpreventing fluid aeration. In operation of the shock absorber 10, itwill be noted that as the piston assembly 26 moves upwardly within thechamber 14, the fluid level therein will also move upwardly, as will thelower end of the baffle member 104, with the result that at least aportion of the member 104 will remain submerged'within the fluid inorder to prevent the undesirable aeration or foaming of the fluid.

Referring now in detail to the construction of the end cap assembly 32,as best seen in FIGS. 1, 2 and 8, the assembly 32 comprises a generallyradially disposed end section 106 which defines a central annular bore108 through which the section 36 of the piston rod 28 extends. Themarginal outer edge of the section 106 is formed with an annular axiallyupwardly extending flange section 110 which is formed with an enlargedthickness or bead portion 112 and with a plurality of circumferentiallyspaced radially outwardly extending openings 114. The diameter of theflange section 110 is slightly smaller than the diameter of the dirtshield member 34 and is thereby adapted to be telescopically or sleevedwithin the lower end thereof, as best seen in FIGS. 1 and 2. The dirtshield member 34 is fabricated of a resilient deformable material, suchas molded rubber or the like, and is thereby adapted to deform or expandradially outwardly in order to accept the flange section within thelower end thereof. The end cap assembly 32 also comprises an annularretaining ring member 116 which is slightly larger in diameter than theflange section 1 l0 and is adapted to be sleeved over the outerperiphery of the lower end of the dirt shield member 34 in the mannershown in FIGS. 1 and 2. The retaining ring member 116 is formed with agenerally radially inwardly disposed shoulder portion 118 around thelower side thereof which is adapted to abut against the underside of theend section 106, as illustrated. In accordance with the presentinvention, in order to positively secure the retaining ring member 116,end section 106 and dirt shield member 34 in a single unitized assemblywhich is secured to the piston rod 28 in the manner hereinabovedescribed, the flange section 110 and member 116 are adapted tocooperate in deformingly securing the lower end of the member 34therebetween. More particularly, upon assembly of the retaining ringmember 116 over the lower end of the dirt shield member 34, a pluralityof radially inwardly projecting, circumferentially spaced, embossedportions, generally designated 120, are formed around the retaining ringmember 116, which embossed portions 120 are radially aligned with theopenings 114 in the flange section 110 in a manner so as to deform theresilient material from which the dirt shield member 34 is fabricatedradially inwardly into the openings 114. The formation of the embossedportions 120 may be accomplished by any suitable crimping or collet typedie or tool arrangement and will be seen to positively fixedly securethe dirt shield member 34 against relative axial movement with respectto the end cap assembly 32. A particular feature of the abovearrangement resides in the fact that the overall diameter or size of thelower end of the shock absorber 10 is kept to a minimum. Additionally,the above described design is pleasant in appearance and obviates theobjectionable outwardly projecting ears which exist when conventionalhose clamps or the like are utilized in securing dirt shields in similartype shock absorber designs. Moreover, the securing arrangement will befound to be substantially more economical than prior known dirt shieldfastening methods.

Referring now in detail to the construction and operation of the rodguide assembly 30, as best seen in FIGS. 6 and 7, the assembly 30comprises an annular body member 122 which is formed with a centralannular bore 124 through which the piston rod 28 extends. The lower endof the bore 124 is formed with an enlarged diameter counterbore 126which defines a gen-' erallyradially disposed shoulder 128. Disposedwithin the counterbore 126 is an annular or sleeve-shaped lining member130 which has the inner periphery thereof slidingly peripherally engagedwith the outer periphery of the piston rod 28, as illustrated. Thelining member 130 is fabricated of a suitable low-friction material,such as teflon which is provided with a suitable rigidifying materialsuch as carbon or the like, whereby to provide for low frictionalresistance of reciprocal movement of the piston rod 28 relative to theassembly 30.

The lining member 130 is adapted to be secured within the body member122 by being axially retained between the shoulder 128 and a wiperassembly, generally designated 132, that is mounted at the lower end ofthe body member 122. The wiper assembly 132 comprises an annular wipermember 134 which is arranged circum jacent the periphery of the pistonrod 28 and is fabricated of a suitable resilient deformable materialsuch as rubber or the like. The member 134 comprises outer and innerperipheral lip portions 136 and 138, respectively, the latter of whichis adapted for compressive engagement with the outer periphery of thepiston rod 28 in a manner so as to wipe any road dirt, moisture or anyother foreign material off from the outer periphery of the piston rod 28as the same moves upwardly into the pressure cylinder 12. Thus, thewiper member 134 prevents any dirt or other foreign material fromingressing between the outer periphery of the piston rod 28 and theinner periphery of the lining member 130 to prevent possible scoring orother damage to the mutually confronting surfaces of either of thesecomponents. The wiper member 134 is adapted to be retained within thelower side of the body member 122 by means of an annular wiper housing140 which is disposed within an enlarged diameter annular counterbore142 formed in the lower side of the body member 122. The housing 140comprises a generally axially extending section 143 which extends aroundthe outer periphery of the lip portion 136 and a generally radiallydisposed flange section 144 which projects radially inwardly above thewiper member 134 and abuttingly engages the lower end of the liningmember 130, as illustrated.

Disposed within the upper end of the body member 122 is an annular fluidseal 146 which is enstingly received within a suitable counterbore 148formed around the upper end of the bore 124. The seal is preferablyprovided with a retaining or garter spring 150 which assures positivesealing engagement thereof with the outer periphery of the piston rod 28to prevent any hydraulic fluid from passing downwardly through the bore124 upon reciprocation thereof. An annular re taining ring 152 isdisposed within a suitablecomplementary-shaped annular recess 153provided in the top of the body member 122 for operatively securing theseal 146 in place.

The entire rod guide assembly 30 is adapted to be received within thelower end of the pressure cylinder 12 and be secured therein by asuitable retaining cap or the like, generally designated 154, which maybe secured over the lower end of the cylinder 12 and be secured theretoby any suitable means. The cap 154 may be provided with a bearing plate156 on the lower side thereof adapted for abutting engagement with aresilient deformable compression bumper 158 which may be provided in thelower end of the dirt shield 34, as illustrated. It may be noted that byvirtue of the fact that the dirt shield member 34 is fabricated of aresilient deformable material, any radially outward expansion of thebumper 158 upon engagement thereof with the plate 156 will result inoutward deformation of the dirt shield member 34 so that there will beno resistance to the cushioning effect of the bumper 158. Additionally,by virtue of the fact that both of the components 138 and 154 arefabricated of a resilient deformable material, there will be nometal-to-metal contact so as to minimize the attendant noise duringoperation of the shock absorber 10. As best seen in FIGS. 6 and 7, the

outer periphery of the body member 122 is formed with an annular,radially inwardly formed recess 160 which is adapted to nestinglyreceive a suitable O-ring 162 or similar type sealing member thatprovides a fluid-tight seal with the inner periphery of the pressurecylinder 12 upon assembly of the body member 122 within the lower endthereof.

In accordance with one of the features of the present invention, inorder to charge or induce pressurized gas into the interior of thechamber 14, a suitable opening or gas port 164 is formed in the wall ofthe cylinder 12 adjacent the lower end thereof, as best seen in FIGS. 9through 11. In order to perform the gas charging operation, the unitizedassembly consisting of the body member 12, O-ring 162, wiper assembly132, liner 130, fluid seal 146 and retaining ring 152, is insertedaxially within the lower end of the pressure cylinder 12 from theposition shown in FIG. 9 to the position shown in FIG. 10. It may benoted that when the aforesaid assemblage is located as shown in FIG. 10,the O-ring sealing member 162 sealingly engages the inner periphery ofthe pressure cylinder 12, yet the upper end of said assemblage does notinterfere with gas being introduced through the port 164 so that thecharging operation can be performed without any of the gas leaking intothe atmosphre through the lower end of the cylin der 12. After thecharging or filling operation has been completed and a predeterminedquantity of pressurized gas has been introduced into the chamber 14, theaforementioned assemblage may be biased axially upwardly when the lowerend of the pressure cyinder 12 from the position shown in FIG. 10 to theposition shown in FIG. 11, which results in the O-ring sealing member162 being moved axially past the port 164 to a position located axiallythereabove, whereby to prevent any gas leakage from the chamber 14through the port 164. The entire assemblage may then be operativelysecured within the lower end of the pressure cylinder 12 by means of asuitable retaining and/or sealing ring 168 which is adapted for nestingreception within a suitable recess 170 defined between the innerperiphery of the cylinder 12 and the outer periphery of the body member122, after which time the retaining cap 154, etc. may be operativelymounted.

While it will be apparent that the preferred embodiment illustratedherein is wellcalculated to fulfill the objects above stated, it will beappreciated that the present invention is susceptible to modification,variation and change without departing from the scope of the invention.

We claim:

1. In combination in a shock absorber,

an elongated cylindrical body member defining a pressure chamber adaptedto contain preselected quantities of hydraulic fluid and a pressurizedgas,

a piston reciprocably disposed within said body member,

a piston rod connected to said piston and extending axially outwardlyfrom one end of said body member,

a combination piston rod guide and closure member adapted to be receivedwith said one end of said body member and defining a central openingwithin which said piston rod is longitudinally slid- I ably disposed,

a radially inwardly extending passage formed in said body memberadjacent said one end thereof for inv troducing a pressurized gaS intosaid chamber, said passage being located in said body member a firtpreselected axial distance from said one end thereof, said closuremember being formed with a radially inwardly extending recess around theouter periphery thereof, an O-ring sealing element disposed in partwithin said recess for providing a gas tight seal between the outerperiphery of said closure member and the inner periphery of said bodymember, said combination rod guide and closure member being axiallymovable within said body member to a partially assembled positionwherein said O-ring sealing element is axially positioned at a secondpreselected axial distance from said one end of said body member, withsaid second axial distance being less than said first axial distancewhereby said sealing element provides a fluid tight seal between saidpassage and said one end of said body member to permit a pressurized gasto be transmitted through said passage into said chamber without leakingout of said body member between said closure member and the adjacentportion of said body member, said combination rod guide and closuremember being axially movable within said body member to a fullyassembled position wherein said O-ring sealing element is axiallypositioned at a third preselected axial distance from said one end ofsaid body member, with said third axial distance being greater than saidfirst axial distance, whereby said sealing element provides a fluidtight seal between said pressure chamber and said passage, and securingmeans for fixedly securing said closure member within said one end ofsaid body member at said fully assembly position 2. The combination asset forth in claim 1 wherein said securing means comprises an annularmember extending around the periphery of said closure member which, uponassembly of said closure member within said body member, is located at afourth axial distance from said one end of said body member, with saidfourth axial distance being less than said first axial distance.

3. The combination as set forth in claim 2 wherein said securing meanscomprises a retaining ring adapted to be nestingly received within aradially extendingrecess formed in one of said members.

4. In the method of assembling a shock absorber comprising an elongatedcylindrical body member adapted to contain preselected quantities ofhydraulic fluid and a pressurized gas, a piston reciprocably disposedwithin the body member, a piston rod connected to the piston andextending axially outwardly from one end of the body member, a closuremember adapted to be axially received within one end of the body memberand defining an opening through which the piston rod extends, a radiallyextending passage located at a first axial distance from the one end ofthe body member for introducing a pressurized gas thereinto, and asealing element carried within a peripheral recess in the closure memberfor providing a gas tight seal between the periphery of the closuremember and the body member, the steps which include,

inserting the closure member into the one end of the body member andmoving the closure member and sealing element to a first axial positionwherein the sealing element is disposed at a second axial distance fromthe end of the body member, with the second axial distance being lessthan the first axial distance, whereby the sealing element will preventpressurized gas being introduced into the interior of the body memberthrough the passage from leaking out of the one end of said body member,

pressurizing the interior of said body member by introducing pressurizedgas thereinto through the passage, and

moving said closure member and sealing element axially inwardly withinthe body member to a second axial position wherein the sealing elementis disposed at a third axial distance from the end of the body member,with the third axialdistance being greater than the first axialdistance, whereby the sealing element will prevent pressurized gaswithin said body member from flowing therefrom through the passage andthe one end thereof.

5. The method as set forth in claim 4 which includes the step of fixedlysecuring the closure member within said one end of said body member atsaid second axial position.

1. In combination in a shock absorber, an elongated cylindrical bodymember defining a pressure chamber adapted to contain preselectedquantities of hydraulic fluid and a pressurized gas, a pistonreciprocably disposed within said body member, a piston rod connected tosaid piston and extending axially outwardly from one end of said bodymember, a combination piston rod guide and closure member adapted to bereceived with said one end of said body member and defining a centralopening within which said piston rod is longitudinally slidablydisposed, a radially inwardly extending passage formed in said bodymember adjacent said one end thereof for introducing a pressurized gasinto said chamber, said passage being located in said body member a firtpreselected axial distance from said one end thereof, said closuremember being formed with a radially inwardly extending recess around theouter periphery thereof, an O-ring sealing element disposed in partwithin said recess for providing a gas tight seal between the outerperiphery of said closure member and the inner periphery of said bodymember, said combination rod guide and closure member being axiallymovable within said body member to a partially assembled positionwherein said O-ring sealing element is axially positioned at a secondpreselected axial distance from said one end of said body member, withsaid second axial distance being less than said first axial distancewhereby said sealing element provides a fluid tight seal between saidpassage and said one end of said body member to permit a pressurized gasto be transmitted through said passage into said chamber without leakingout of said body member between said closure member and the adjacentportion of said body member, said combination rod guide and closuremember being axially movable within said body member to a fullyassembled position wherein said O-ring sealing element is axiallypositioned at a third preselected axial distance from said one end ofsaid body member, with said third axial distance being greater than saidfirst axial distance, whereby said sealing element provides a fluidtight seal between said pressure chamber and said passage, and securingmeans for fixedly securing said closure member within said one end ofsaid body member at said fully assembly position
 2. The combination asset forth in claim 1 wherein said securing means comprises an annularmember extending around the periphery of said closure member which, uponassembly of said closure member within said body member, is located at afourth axial distance from said one end of said body member, with saidfourth axial distance being less than said first axial distance.
 3. Thecombination as set forth in claim 2 wherein said securing meanscomprises a retaining ring adapted to be nestingly received within aradially extending recess formed in one of said members.
 4. In themethod of assembling a shock absorber comprising an elongatedcylindrical body member adapted to contain preselected quantities ofhydraulic fluid and a pressurized gas, a piston reciprocably disposedwithin the body member, a piston roD connected to the piston andextending axially outwardly from one end of the body member, a closuremember adapted to be axially received within one end of the body memberand defining an opening through which the piston rod extends, a radiallyextending passage located at a first axial distance from the one end ofthe body member for introducing a pressurized gas thereinto, and asealing element carried within a peripheral recess in the closure memberfor providing a gas tight seal between the periphery of the closuremember and the body member, the steps which include, inserting theclosure member into the one end of the body member and moving theclosure member and sealing element to a first axial position wherein thesealing element is disposed at a second axial distance from the end ofthe body member, with the second axial distance being less than thefirst axial distance, whereby the sealing element will preventpressurized gas being introduced into the interior of the body memberthrough the passage from leaking out of the one end of said body member,pressurizing the interior of said body member by introducing pressurizedgas thereinto through the passage, and moving said closure member andsealing element axially inwardly within the body member to a secondaxial position wherein the sealing element is disposed at a third axialdistance from the end of the body member, with the third axial distancebeing greater than the first axial distance, whereby the sealing elementwill prevent pressurized gas within said body member from flowingtherefrom through the passage and the one end thereof.
 5. The method asset forth in claim 4 which includes the step of fixedly securing theclosure member within said one end of said body member at said secondaxial position.